NeRF-SLAM Fixes

[uy-seng]

Here is the environment specs that I tested on:

• CUDA 11.3
• cmake version 3.28.1

Updates include:

• Add fixes instruction in README.md that include how to fix dependency issues for instant-ngp and gtsam and alternate ways to install setup.py.
• setup.py is being updated to install droid-backends only, we can install lietorch using requirements.txt
• Replace broke gtsam functions with the correct function
• Fixes scripts/download_replica_sample.sh
• Added colored_glog and lietorch to requirements.txt

You should be able to run NeRF-SLAM properly by applying the above fixes.

Feel free to add any comments regarding any issue you encountered after applying the fixes using this branch feature/nerf-slam-revised